Docker聚集了多个管理人员和工作人员 [英] Docker swarm multiple managers and workers Vs

问题描述

我有一个3节点的docker swarm集群。我们可能想要2位经理。我知道一次只有一位领导人。由于它是一个3节点的集群，因此我试图寻找一些文献来了解多管理者的优缺点。我需要此信息，因为在我的3节点集群中，如果我有2个主节点，1个工作线程，那么如果我仅在集群中创建3个主节点，将会带来什么不利影响。任何想法都会有所帮助。

I have a 3 node docker swarm cluster. We might want to have 2 managers. I know at one time there is only one leader. Since it is a 3 node cluster, I am trying to find some literature to understand what are the pros and cons of multiple managers. I need this info since in my 3 node cluster if I have 2 masters, 1 worker, what is the downside if I simply create 3 masters in a cluster. Any thoughts would be helpful.

推荐答案

不推荐使用具有两个管理器的Docker集群 。

A Docker swarm with two managers is not recommended.

为什么？

Docker swarm实施RAFT共识：

筏最多可承受（N- 1）/ 2个失败，并且需要（N / 2）+1个成员的多数或法定人数来同意向集群提出的值。这意味着在由5个运行Raft的Manager组成的集群中，如果3个节点不可用，则系统将不再处理任何调度其他任务的请求

Raft tolerates up to (N-1)/2 failures and requires a majority or quorum of (N/2)+1 members to agree on values proposed to the cluster. This means that in a cluster of 5 Managers running Raft, if 3 nodes are unavailable, the system will not process any more requests to schedule additional tasks

如果有2位管理者，则其中一个宕机，另一个将无法安排其他任务（无集群升级，无新服务等。）。

So with 2 managers, if one is down, the other will not be able to schedule additional tasks (no cluster upgrades, no new services, etc...).

文档也很清楚关于您应该拥有的高级管理人员数量可用性：

调整部署大小

Size your deployment

要使群集能够承受更多故障，请添加其他副本

To make the cluster tolerant to more failures, add additional replica nodes to your cluster.

Manager nodes Failures tolerated
    1                 0
    3                 1
    5                 2
    7                 3

因此，简而言之，如文档所述此处：

So in brief, as the doc states here:

添加更多管理员并不意味着增加可扩展性或更高的性能。通常，情况恰恰相反。

Adding more managers does NOT mean increased scalability or higher performance. In general, the opposite is true.

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